Design of a nested eight-channel sodium and four-channel proton coil for 7T knee imaging

Ryan Brown, Guillaume Madelin, Riccardo Lattanzi, Gregory Chang, Ravinder R. Regatte, Daniel K. Sodickson, Graham C. Wiggins

Research output: Contribution to journalArticlepeer-review


The critical design aim for a sodium/proton coil is to maximize sodium sensitivity and transmit field homogeneity while simultaneously providing adequate proton sensitivity and homogeneity. While most dual-frequency coils use lossy high-impedance trap circuits or PIN diodes to allow dual-resonance, we explored a nested-coil design for sodium/proton knee imaging at 7 T. A stand-alone eight-channel sodium receive array was implemented without standard dual-resonance circuitry to provide improved sodium signal-to-noise ratio. A detunable sodium birdcage was added for homogeneous sodium excitation and a four-channel proton transmit-receive array was added to provide anatomical reference imaging and B0 shimming capabilities. Both additional modules were implemented with minimal disturbance to the eight-channel sodium array by managing their respective resonances and geometrical arrangement. In vivo sodium signal-to-noise ratio was 1.2-1.7 times greater in the developed eight-channel array than in a mononuclear sodium birdcage coil, whereas the developed four-channel proton array provided signal-to-noise ratio similar to that of a commercial mononuclear proton birdcage coil.

Original languageEnglish (US)
Pages (from-to)259-268
Number of pages10
JournalMagnetic resonance in medicine
Issue number1
StatePublished - Jul 2013


  • cartilage
  • dual-tuned coil
  • high-field sodium MRI
  • phased-array

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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